The users of computers, Personal Digital Assistants (PDAs), and other data processing equipment increasingly rely upon various types of network connections in order to obtain access to data in various forms. For example, sophisticated business users now desire high speed Internet access whether on the road or in their home location. Corporate information technology departments often need to rapidly set up and tear down access for their users as locations change and temporary visitors need to be accommodated. In addition, organizations in the appliance repair, package delivery, and other service industries also require data access.
Although present wireless communication infrastructure such as provided by the cellular telephone network is in widespread use for voice traffic, its use has not spread in particular for data applications. This is due in part perhaps to the relatively slow available speeds for sending data over cellular connections, which supports rates of only 9600 or 14400 baud. Another consideration is convenience. For example, in order to use the cellular system, one must not only carry around a cellular telephone, but also specialized modem equipment in addition to a laptop computer or other personal computing equipment.
Digital cellular equipment typically makes use of handsets that have the traditional single dipole antenna. Unfortunately, such antenna units are not optimized for maximizing data speeds. For example, in networks that make use of Code Division Multiple Access (CDMA) signaling, power levels must be carefully controlled, especially for transmission from the subscriber back to the base station (reverse link). By optimizing the effective radiated power, data rates can be maximized.
Unfortunately, known dipole antenna arrangements, or even known combinations of dipole arrangements, do not provide adequate control over effective radiated power. This is due in part to a number of causes. Dipole antennas alone do not provide directional antenna patterns that allow the power to be more effectively directed to the base station. Moreover, implementing such devices within handset form factors, or within other form factors such as integral to the case of the computer equipment, makes it difficult to ensure that the antenna elements are properly oriented with respect to the earth.
What is needed is a small and convenient unit that can be used to provide wireless data access such as over existing cellular telephone networks. The device should have a convenient form factor such as will fit in a shirt pocket or purse.
The present invention is a miniaturized directional antenna array that can be used to provide directional gain to optimize digital data communications. The antenna array is packaged in a palm sized case which may be placed on a table or other approximately horizontal surface convenient to the portable computing equipment. The arrangement of the array elements within the case automatically provides a proper orientation of the antenna elements with respect to the earth.
In the preferred embodiment, the array is a five element array having a center element and four outlying or comer elements. The outlying elements are spaced at approximately one-quarter of a wave length radial distance from the center element. The antenna elements are fastened to an appropriate support structure disposed within the case which is formed of a convenient material such as plastic which is transparent to radio wave propagation. Other electrical elements such as strip line power dividers, phase shifter components, and power routing components are placed on a multilayer printed circuit card disposed beneath the antenna array support structure.
In the preferred embodiment, the radiating elements themselves are a type of miniaturized antenna element known as a multilayer chip antenna. Such chip antennas are extremely small in size and may be conveniently mounted within the support structures in accordance with well known manufacturing techniques.
Alternatively, the radiating elements may be helical antennas that are also mounted within the support structure with the proper vertical orientation.
The overall result is an antenna package that does not exceed approximately one (1) inch in height and three (3) inches in width and depth, which can be used to greatly enhance the radio link signaling characteristics for data signals.